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A206694 Number of n X 2 0..2 arrays avoiding the pattern z-2 z-1 z in any row or column. 3
9, 81, 676, 5625, 46656, 386884, 3207681, 26594649, 220492801, 1828075536, 15156318321, 125658906256, 1041820324416, 8637585806529, 71613009227809, 593733388556025, 4922560027477764, 40812252925262329, 338368649551172496 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A206700.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 9*a(n-1) -3*a(n-2) -25*a(n-3) +9*a(n-4) +3*a(n-5) -a(n-6).

Empirical g.f.: x*(9 - 26*x^2 + 9*x^3 + 3*x^4 - x^5) / ((1 - 9*x + 6*x^2 - x^3)*(1 - 3*x^2 - x^3)). - Colin Barker, Feb 23 2018

EXAMPLE

Some solutions for n=4:

..0..1....0..2....0..2....2..0....0..2....2..1....0..1....1..1....1..2....1..2

..2..1....2..2....1..1....0..2....0..2....0..2....2..1....1..0....2..2....2..0

..2..2....0..0....0..0....1..0....2..2....1..2....2..0....1..2....1..2....0..1

..0..0....2..1....0..1....1..2....0..2....0..1....0..1....1..2....2..2....1..0

CROSSREFS

Cf. A206700.

Sequence in context: A206728 A206857 A073531 * A125910 A171283 A174108

Adjacent sequences:  A206691 A206692 A206693 * A206695 A206696 A206697

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 11 2012

STATUS

approved

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Last modified October 6 12:00 EDT 2022. Contains 357264 sequences. (Running on oeis4.)